Disclosed in embodiment herein are methods and apparatuses relating to an image forming machine, and more particularly, to a xerographic image forming machine having one or more marking engines with developers having dual replenisher assemblies providing a higher gloss and a lower gloss toner for achieving variable gloss.
A typical electrophotographic, or xerographic, printing machine employs a photoreceptor, that is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoreceptor is exposed to a light image of an original document being reproduced. Exposure of the charged photoreceptor selectively dissipates the charge thereon in the irradiated areas to record an electrostatic latent image on the photoreceptor corresponding to the image contained within the original document. After the electrostatic latent image is recorded on the photoreceptor, the latent image is developed by bringing a developer material into contact therewith. Generally, the electrostatic latent image is developed with dry developer material, referred to as toner, comprising toner particles which are attracted to the latent image, forming a visible powder image on the photoconductive surface. After the electrostatic latent image is developed with the toner particles, the toner powder image is transferred to a sheet, such as paper or other substrate sheets, using pressure and heat to fuse the toner image to the sheet to form a print.
Toner has several fused characteristics which determine qualities of the resulting image print. The color a toner produces in a print is one characteristic. Another is the gloss level of the fused toner in the print, also referred to as gloss. Toners typically produce a fairly consistent gloss level, with high gloss toners being used to produce glossy prints and low gloss toners being used to produce low gloss, or matte prints.
It can be desirable to manipulate the gloss of printed images. However, a single toner has a fixed range of gloss that depends on fusing parameters such as the fuser roll temperature, substrate and age of the fuser. Thus the user has little latitude to change the gloss of the toner on any particular substrate. Also, gloss can vary with time as the fuser ages. Current options for changing gloss can include changing the fuser temperature/dwell by changing the fuser setpoint and/or print speed. This allows some latitude to change gloss, but can affect productivity (if the speed is lowered), or fuser life (if temperature is increased) or image permanence (if speed is increased or fuser roll temperature is decreased). Another option can include changing out the developer housing and the replenisher bottle with a toner of a different gloss. Yet another option can include adding an additional developer housing, such as for example, a 5th housing in CMYK printing, and apply an overcoat with a different gloss than that used to image the toner.
It is desirable, therefore, to improve a xerographic image forming machine to provide variable control over the range of gloss levels available in the printed color image.